356 The Silurian System. 



satisfied themselves that the region called Cambria, at a time, it 

 will be recollected, when none of its fossils were described, is made 

 up of the same strata, and contains the same organic remains, as the 

 lower Silurian rocks, whose contents were so long ago described by 

 myself. Inquiries and researches in various parts of Europe, in 

 which I have taken part, and in America and other countries, have 

 been followed by similar results ; and as the lower Silurian types 

 of life have everywhere proved to be the oldest, the term Cambrian 

 has never yet been applied to strata characterised by any group of 

 animals peculiar to them. 



The adoption of the proposal of Professor Sedgwick would, in 

 truth, destroy the Silurian system of rocks. For whilst he leaves 

 me the Caradoc sandstone, he would cut away from it the next un- 

 derlying formation, or my own Llandeilo flags ; though it is known 

 to every one who has worked in these primeval rocks, that many of 

 the same species of shells and trilobites characterise both the Caradoc 

 and Llandeilo formations. How, then, is the geologist to draw any 

 line of separation through the middle of a group, the members of 

 which are thus naturally united ? How call one part of it Silurian, 

 and another Cambrian ? How, indeed, break up a natural system of 

 life in which a great number of fossils are found to be common to 

 its upper and lower divisions 1 



That the Silurian base-line, on which Professor Sedgwick lays so 

 much stress, was inaccurately defined in many parts when my labours 

 in Siluria terminated, is very true ; but it was essentially correct in 

 Shropshire, and all that might lie beneath it was left to himself to 

 determine. The chief phenomena I described in Siluria, after seven 

 years of labour, have stood the test of time ; and a companion whose 

 friendship I shall never cease to value, must not lay to my door the 

 loss of a Cambrian kingdom, in the occupation of which I had no 

 share. Its invaders have been the geological surveyors, who lite- 

 rally could not do otherwise than inteipret a region (the fossil con- 

 tents of which had never been delineated) exct-pt by comparing it 

 with tracts long well known, through my detailed descriptions of their 

 rocks and fossils. These surveyors have shewn, that the very strata 

 which in Shropshire and Montgomeryshire I described as lower Silu- 

 rian, to the west of my " Cambrian" Longmynd, roll over in great 

 undulations to Snowdon itself. Hence it is now useless to refer back 

 to the inaccurate portion of a line of boundary on my old map, which 

 is little more than a demarcation between my own hunting-grounds 

 and those of my friend. Cambria was, indeed, his own country, in 

 which, amid grand contortions of the rocks, he had ably mastered 

 many physical difficulties besides those of slaty cleavage : and I re- 

 spected this territory, in the full persuasion that its strata would prove 

 to be of higlier antiquity than my own, and, if so, that their contents 

 would be distinct. The appeal to nature by our associates has de- 

 cided otherwise. 



